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The binary stars of Alpha Centauri, as seen from Saturn

Earlier this week, we learned that there is (most likely) at least one planet orbiting the star Alpha Centauri B. If you want to get really in-depth on this discovery, how it was made, and what it means, you should be reading Paul Gilster's Centauri Dreams blog.

I wanted to highlight this image, specifically, in order to quote some particularly evocative writing that Gilster posted yesterday. Cue the stirring music:

When planet-hunter Greg Laughlin (UC-Santa Cruz) took his turn at the recent press conference announcing the Alpha Centauri B findings, he used the occasion to make a unique visual comparison. One image showed the planet Saturn over the limb of the Moon. Think of this as the Galilean baseline, for when Galileo went to work on the heavens with his first telescope, the Moon was visually close at hand and Saturn a mysterious, blurry object with apparent side-lobes.

Laughlin contrasted that with [this image], showing the Alpha Centauri stars as viewed from Saturn, a spectacular vista including the planet and the tantalizing stellar neighbors beyond. Four hundred years after Galileo, we thus define what we can do — a probe of Saturn — and we have the image of a much more distant destination we’d like to know a lot more about. The findings of the Geneva team take us a giant step in that direction, revealing a small world of roughly Earth mass in a tight three-day orbit around a star a little smaller and a little more orange than the Sun. What comes next is truly interesting, both for what is implied and for what we are capable of doing.

Read the rest of this post, which explains what happens next with the research and why astronomers will be focusing their planet-hunting efforts on Alpha Centauri B.

Why you should care about the planet found orbiting Alpha Centauri, even though it's not a good place to live

Last night, astronomers with the European Southern Observatory announced that they'd found a planet orbiting Alpha Centauri B — an orange star a little smaller and a little less bright than our own Sun. That's important, because, while more than 700 planets have been found outside our solar system, this one — Alpha Centauri Bb (yeah, I know) — is by far the closest. To give you an idea of what we're talking about in distance here, imagine that we are Kansas City and Mars is Toledo. Alpha Centauri Bb is like Tokyo — but you have to get there the long way around and nobody has invented the boat or the plane yet. Basically, it's closer than any other planet we know of outside our solar system, but not really close close. Just 4.37 light years is still more than 25 trillion miles, which is still a long ways away.

Likewise, Alpha Centauri Bb is classified as an "Earth-like" planet, but that shouldn't give you any ideas of colonizing it Zefram Cochrane-style. Bb is way too close to its star for that — closer, even, than Mercury is to our own Sun.

But you should still be excited about this. Terrible, filing-cabinet name aside, Alpha Centauri Bb is jeffing epic. Until now, we didn't think our closest neighboring solar system had any planets at all. And because of the way planets work, writes Lee Billings at the Centauri Dreams blog, this single find means we're much, much more likely to discover other Centaurian worlds. Billings is a former guest blogger here at BoingBoing and his work on exoplanets is second to none. I highly recommend reading his full piece:

Anyone in the Southern Hemisphere can look up on a clear night and easily see Alpha Centauri — to the naked eye, the three suns merge into one of the brightest stars in Earth’s sky, a single golden point piercing the foot of the constellation Centaurus, a few degrees away from the Southern Cross. In galactic terms, the new planet we’ve found there is so very near our own that its night sky shares most of Earth’s constellations. From the planet’s broiling surface, one could see familiar sights such as the Big Dipper and Orion the Hunter, looking just as they do to our eyes here.

Read Lee Billings' full post about Alpha Centauri Bb, and keep an eye on the Centauri Dreams blog for further updates/analysis.

Read Phil Plait's take at Bad Astronomy

A helpful NASA primer on distance in space

• In the late 1980s, NASA considered sending an unmanned probe to Alpha Centauri B. It would have taken 100 years to get there, using nuclear explosions to create thrust.

Image: Marco Lorenzi via NASA's Astronomy Picture of the Day